Explanation: Gamma
rays are the most energetic form of light, packing a million
or more times the energy of visible light photons.
If you could see gamma rays,
the familiar skyscape of steady stars would
be replaced by some of the
most bizarre objects
known
to modern astrophysics -- and
some which are unknown.
When the EGRET instrument on the orbiting
Compton Gamma-ray Observatory surveyed
the sky in the 1990s, it cataloged 271
celestial
sources of high-energy gamma-rays.
Researchers identified some
with exotic black holes,
neutron stars, and distant
flaring galaxies.
But 170 of the cataloged sources, shown
in the above all-sky map, remain unidentified.
Many sources in this gamma-ray mystery map likely
belong to already known classes of gamma-ray emitters and are simply
obscured or too faint to be otherwise positively identified.
However, astronomers
have called attention to the ribbon
of sources winding through the plane of the
galaxy, projected here along the middle of the map, which
may represent a large
unknown
class of galactic gamma-ray emitters.
In any event, the unidentified sources could remain a mystery
until the planned launch of the more sensitive
Gamma-ray Large
Area Space Telescope in 2007.